College of Resource and Environment, Hunan Agricultural University, Changsha, 410128, Hunan, People's Republic of China.
College of Life Sciences and Environment, Hengyang Normal University, Hengyang, 421008, Hunan, People's Republic of China.
Environ Sci Pollut Res Int. 2019 Jun;26(17):17655-17665. doi: 10.1007/s11356-019-05134-w. Epub 2019 Apr 26.
Heavy metals including copper (Cu), zinc (Zn), cadmium (Cd), chromium (Cr), lead (Pb), and arsenic (As) were investigated in 89 pairs of rice plant and paddy soils around Dongting Lake area, China. Rice plants and soils were collected with GPS device, and heavy metal contents in different rice plant tissues and soils were measured. The aim of the present study was to assess the heavy metal pollution and translocation in the whole soil-rice system, including the consequent human health risk for residents. According to the indices of average geoaccumulation (I) of the studied elements, paddy soils in study area were moderately polluted by Cd, lowly polluted by Pb, and not polluted by Cu, Zn, Cr, and As. Considering the much higher concentrations of studied elements in roots than in other tissues of rice plants, a great mass of these elements was assumed to be confined in the roots. The low translocation factors from root to shoot (Tf) of all the studied heavy metals (0.04-0.74) underpinned this. The high translocation factors from soil to root (Tf) of Cd (9.12), As (4.38), and Zn (2.05) indicated the high bioavailability of these heavy metals for rice plant. The health risk assessment using target hazard quotients (THQs) model indicated that Cd (5.17 for adults and 4.49 for children respectively) and As (3.61 for adults and 3.14 for children respectively) could cause human health risk both for adults and children. Further, given the rate of individual THQ values exceeding one, Cu might also be considered as a potential human health dangerous element in the study area. It was worth noting that as one of the main pollutants, Pb did not show human health risk through rice grain consumption due to its low Tf values in soil-rice system. However, the risk identification of As using comparisons of measured concentrations with risk screening value in Chinese paddy soil standard (GB15618-2018) was not consistent with the human health risk assessment result. This might indicate that site-specific risk screening values of As in China is in demand.
在中国洞庭湖地区，研究人员调查了 89 对水稻植株和稻田土壤中的重金属，包括铜（Cu）、锌（Zn）、镉（Cd）、铬（Cr）、铅（Pb）和砷（As）。利用 GPS 设备采集水稻植株和土壤样本，测量不同水稻植株组织和土壤中的重金属含量。本研究旨在评估整个土壤-水稻系统中的重金属污染和迁移，包括对当地居民的健康风险。根据研究元素的平均地质累积指数（I），研究区域的稻田土壤受到 Cd 的中度污染，受到 Pb 的低度污染，而 Cu、Zn、Cr 和 As 则未受到污染。考虑到研究元素在水稻根系中的浓度远高于其他组织，大量这些元素可能被限制在根系中。所有研究重金属的根到茎的迁移系数（Tf）都较低（0.04-0.74），这也支持了这一假设。Cd（9.12）、As（4.38）和 Zn（2.05）从土壤到根系的高迁移系数（Tf）表明这些重金属对水稻植株具有较高的生物可利用性。利用目标危害系数（THQ）模型进行健康风险评估表明，Cd（成人分别为 5.17 和儿童分别为 4.49）和 As（成人分别为 3.61 和儿童分别为 3.14）都可能对成人和儿童造成健康风险。此外，鉴于个别 THQ 值超过 1 的比例，Cu 也可能被认为是该研究区域的一个潜在的对人类健康有危险的元素。值得注意的是，作为主要污染物之一，Pb 由于其在土壤-水稻系统中的低 Tf 值，并未通过食用稻谷而对人体健康造成风险。然而，用中国稻田土壤标准（GB15618-2018）中的风险筛选值与实测浓度进行比较来识别 As 的风险，与人体健康风险评估结果并不一致。这可能表明，中国需要制定特定地点的 As 风险筛选值。
